(a) Field of the Invention
This invention relates to 3-methyl-4-(4-pyridinyl)-benzeneamines, which are useful as cardiotonic agents, to cardiotonic compositions containing the same, a method of increasing cardiac contractility using the same and to chemical processes for the preparation thereof.
(b) Description of the Prior Art
Koenigs et al., Ann., 509, 142-158 (1934) disclose, on pages 147-148, the preparation of 4-(4-pyridinyl)-N,N-dimethylbenzeneamine for which no utility is asserted. The compound is prepared by heating on a water bath a mixture of 16 g. (0.202 mole) of pyridine with 14 g. (0.099 mole) of benzoyl chloride in the presence of 0.5 g. (0.0079 mole) of copper powder and then treating the cooled reaction mixture with 12 q. (0.098 mole) of N,N-dimethylbenzeneamine (i.e. N,N-dimethylaniline) followed by heating for five hours on a water bath, the ratio of pyridine to benzoyl chloride to dimethylaniline to copper thus being 2:1:1:0.079. However in a section on pages 150-151 entitled (in translation) "Condensation Products from m-Dimethylamino-toluene, Pyridine and Benzoyl Chloride", the authors describe a similar reaction using the same reaction conditions and precisely the same molar ratios of reactants, except that 3-methyl-N,N-dimethylbenzeneamine (i.e. dimethyl-m-toluidine) was used in place of the N,N-dimethylbenzeneamine used in the procedure described on pages 147-148 of the reference. The product obtained is identified only by its empirical formula, which corresponds, not to 3-methyl-4-(4-pyridinyl)-N,N-dimethylbenzeneamine, which would result if the reaction followed the same course as the reaction using N,N-dimethylbenzeneamine, but rather to a compound of unknown composition having the empirical formula C.sub.21 H.sub.21 N.sub.2 OCl.
British Patent 518,886 discloses 2-methyl-4-(4-pyridinyl)benzeneamine, useful as an intermediate for the preparation of dyestuffs, and Forsythe et al., J. Chem. Soc., 2921 (1926) disclose 4-(4-pyridinyl)benzeneamine, for which no utility is given.